= key brain areas of the emotional brain
What happens in amygdala in
basolateral nuclei
central nuclei
get info from all systems
decide about the emotional relevance
information conduction to Hypothalamus, PAG, Cerebral Cortex
Which inputs and outputs do we have? What are their functions
Hypothalamus
Autonomic response
PAG
behavioural reaction
Cerebral Cortex
emotional experience
auditory cortex input + cortical inputs in general
What happens when PAG is activated during
fear
aggression
Amygdala —> PAG
Freezing, Flight
Hypothalamus —> affective aggressions
What happens beyond the emotions when PAG is activated during fear/aggression?
—> raphe nuclei (Medulla) —> serotonine —> dorsal horn of the spinal cord —> nociceptors inhibited
= pain response is modulated too
What is the neuronal network of fear conditioning in the amygdala? e.g. tone + shock
Tone —> auditory thalamus (MGN) —> auditory cortex
food shock —> somatosensory thalamus (VP/intraluminar nuclei) —> somatosensory cortex
somatosensory cortex+auditory cortex —> Amygdala —> lateral nuclei —> basolateral nuclei —> central nuclei
—> Hypothalamus —> Fear response (Sympathikus)
What happens with this neuronal network when the neutral stimulus tone got to a conditioned stimulus?
fear response
CS —> CR
What is extinction learning?
CS + without US (repeat)
CS —> decay of CR
vmPFC inhibits the amygdala → CR is suppressed (not erased)
What is the prediction error?
Determines whether an association becomes stronger (positive PE) or weaker (negative PE)
Dopamine neurons in the VTA encode reward prediction errors
send to Amygdala, the medial prefrontal cortex (mPFC) and the striatum
Extinction memory is associated with increased vmPFC activity —> suppresses amygdala-mediated fear responses
What is the mesocortical limbic dopamine system?
ventral tegmental area (Midbrain)
—> PFC
—> limbic system (amygdala)
= reward system
Which additional system plays a role in extinction learning?
endocannabinoidsystem (CB1-receptors)
Is PFC involved in
fear learning
extinction learning
no
yes!
What´s the problem with stress response?
inhibits PFC - amygdala connection
—> extinction learning impaired
What is the emotional function of the PFC in general?
= cognitive cortical control
e.g. can suppress the amygdala reaction
Which emotions are associated with PFC and amygdala mostly?
PFC
sadness
amygdala
Which structure is a node point for connecting emotions? What´s the main function? How is this structure connected?
Anterior Cingulate Cortex (ACC) = part of the PFC
connects generated emotions with HPA axis
connected to
Amygdala
Hippocampus
What is the HPA axis?
= Paraventricular nucleus
corticotropin releasing hormone (CRH) neurons
Pituitary
= corticotrophin cells
adrenocorticotropin releasing hormone (ACTH)
Adrenal glands
= adrenal cortex cells
glucocorticoids
—> Cortisol in humans
—> Corticosterone in mice
How is the PFC influencing the amygdala?
PFC - amygdala = top-down
PFC = cognitive control of emotions
(e.g. hyperactivity in PFC = hyperactivity in amygdala)
How is the amygdala influencing the PFC?
amygdala - PFC = bottom-up
fast reaction to threat
What´s the way of emotions in general?
Sensory stimulus → Amygdala (basolateral nuclei)
Evaluation & Control: Communication between the amygdala, PFC (ACC)
ACC function: Links the state of the PFC to the physical stress response
Central nucleus of the amygdala → hypothalamus (hormones/autonomic nervous system), PAG (behavior)
Feedback: Projections back to the cortex for conscious sensation
What is aggression?
Affective aggression
= emotional, impulsive, high sympathetic nervous system activity
(angreifen for show)
Predatory aggression
= goal-oriented, no sympathetic activation
(angreifen für food)
Which brain areas are involved in aggression?
Cortex: orbitofrontal cortex
Amygdala: MEA = medial amygdala
Extended amygdala: BNST = Bed nucleus of stria terminalis
Hypothalamus: AHA = Anterior hypothalamic area
Brain stem: PAG = output
What is the general pathway of aggression?
Olfactory bulb → amygdala → hypothalamus → brainstem (PAG) → aggressive behavior
What regulates aggression?
Serotonin
low 5-HT → high impulsivity, aggression
—> “optimal” levels of 5-HT is required (also during development)
Why is PFC important in aggression?
Prefrontal control over the amygdala is crucial for impulse control
—> low serotonin levels impair this inhibition
What is attention?
= state of selectively processing simultaneous sources of information
What is ADHD?
Inattention + hyperactivity + impulsivity
—> structural changes in the prefrontal cortex and basal ganglia (smaller)
genetic
D2 and D4 dopamine receptors and the dopamine transporter are affected
treatment: Ritalin inhibits dopamine transporter —> more dopamine in synaptic cleft
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